Variable force solenoid operated valve assembly with dampener

Abstract

A variable force solenoid operated pressure control valve of the type having a force balanced spool moveably controlled energization of the solenoid for modulating the discharge pressure of the valve at its control outlet when the valve is supplied at its inlet with fluid of a supply pressure. The spool is moved to bleed fluid through an exhaust port to a sump for controlling the pressure supplied to the control outlet. The spool has a dashpot and piston in one end for providing hydraulic dampening of spool oscillations. In one embodiment a cylindrical piston is used and in an alternate arrangement a ball is employed in the dashpot.

We claim: 
     
       1. A variable force solenoid operated valve assembly for providing a control pressure at an outlet from an inlet supply pressure in response to an electrical signal to the solenoid comprising: (a) a valve body having an inlet passage adapted for connection to a fluid source at supply pressure, an outlet passage supplying fluid at a control pressure adapted for communication with a system to be controlled, an exhaust passage adapted for connection to a sump, and a valving bore communicating with each of said passages in axially spaced arrangement;   (b) a spool valve moveably disposed in said valving bore and having a first annular land defining a first chamber communicating with said inlet passage, a second annular land defining a second chamber communicating with said outlet passage and a third annular land stepped from said second land defining a third chamber communicating with said exhaust passage, said spool having a blind bore formed in an end thereof with a piston moveably received therein in closely fitting arrangement including means biasing said piston outwardly of said blind bore, said spool including a port communicating said blind bore with said second chamber;   (c) a first restriction means associated with said second annular land for controllably restricting fluid communication between said first chamber and said second chamber;   (d) a second restriction means associated with said third annular land for controllably restricting fluid communication between said second chamber and said third chamber; and,   (e) a solenoid assembly including a coil, an armature and a flux collector for providing a flux loop about said coil spaced from said armature, said armature operably contacting said spool valve for effecting movement thereof in response to controlled energization of said coil, and means biasing said armature in a direction away from said flux collector; and, (f) a stop for limiting said outward movement of said piston, whereby controlled energization of said solenoid coil effects movement of said armature and movement of said spool valve in a direction to cause said first restriction to decrease fluid communication between said first and second chamber and cause said second restriction to increase communication between said second and third chambers with said piston closely fitted in said blind bore such that said piston and blind bore function as a dashpot for dampening transient movement of said spool.   
     
     
       2. The valve assembly defined in claim 1, wherein said flux collector is adjustable for varying said air gap. 
     
     
       3. The valve assembly defined in claim 1, wherein said spool port comprises a metering orifice. 
     
     
       4. The valve assembly defined in claim 1, wherein said spool valve is vented to sump at opposite ends. 
     
     
       5. The valve assembly defined in claim 1, wherein said flux collector includes a generally tubular member having at least one void therein and a plug member having at least one recess therein received in said tubular member, said plug rotatable for varying the orientation of said recess to said void for varying the flux across said air gap.